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691.
G. Yuan D. Chen L. Yin Z. Wang L. Zhao J.Y. Wang 《Waste management (New York, N.Y.)》2014,34(6):1045-1050
In this research a gas–liquid fluidized bed reactor was developed for removing chlorine (Cl) from polyvinyl chloride (PVC) to favor its pyrolysis treatment. In order to efficiently remove Cl within a limited time before extensive generation of hydrocarbon products, the gas–liquid fluidized bed reactor was running at 280–320 °C, where hot N2 was used as fluidizing gas to fluidize the molten polymer, letting the molten polymer contact well with N2 to release Cl in form of HCl. Experimental results showed that dechlorination efficiency is mainly temperature dependent and 300 °C is a proper reaction temperature for efficient dechlorination within a limited time duration and for prevention of extensive pyrolysis; under this temperature 99.5% of Cl removal efficiency can be obtained within reaction time around 1 min after melting is completed as the flow rate of N2 gas was set around 0.47–0.85 Nm3 kg?1 for the molten PVC. Larger N2 flow rate and additives in PVC would enhance HCl release but did not change the final dechlorination efficiency; and excessive N2 flow rate should be avoided for prevention of polymer entrainment. HCl is emitted from PVC granules or scraps at the mean time they started to melt and the melting stage should be taken into consideration when design the gas–liquid fluidized bed reactor for dechlorination. 相似文献
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694.
Pesticide leaching models are being used to assist in the regulation and management of pesticides by indicating their potential for leaching to groundwater. Uncertainty in model input data is not, regrettably, included in most pesticide leaching assessments. In the work described here, we use logarithmic transformations of the attenuation factor (AF), a simple process-based index model, to represent uncertainty in a pesticide leaching assessment. Characterization of a wide range of pesticides as `leachers' or `non-leachers' for a specific Hawaii hydrogeological setting is facilitated by comparing the log-transformed AF, designated AFR, for each chemical with two reference chemicals for which leaching behavior in Hawaii is known. Defining a mean and uncertainty interval for the AFR index of each chemical being ranked provides a practical method of incorporating data uncertainty into a regulatory protocol. 相似文献
695.
Z. M. Grahovac S. S. Mitić E. T. Pecev A. N. Pavlović 《Journal of environmental science and health. Part. B》2013,48(8):783-789
In the present study, a new sensitive and simple kinetic-spectrophotometric method for the determination of the insecticide diflubenzuron [1-(4-chlorophenyl)-3-(2,6-diflubenzoil)urea] is proposed. The method is based on the inhibited effect of diflubenzuron on the oxidation of sulphanilic acid (SA) by hydrogen peroxide in phosphate buffer in presence Cu(II) ion. Diflubenzuron was determined with linear calibration graph in the interval from 0.31 to 3.1 μg mL?1 and from 3.1 to 31.0 μg mL?1. The optimized conditions yielded a theoretical detection limit of 0.18 μg mL?1corresponding to 0.036 mg Kg?1mushroom sample based on the 3Sb criterion. The RSD is 5.03–1.83 % and 2.81–0.71 % for the concentration interval of diflubenzuron 0.31–3.1 μg mL?1and 3.1–31.0 μg mL?1, respectively. The reaction was followed spectrophotometrically at 370 nm. The kinetic parameters of the reaction are reported, and the rate equations are suggested. The developed procedure was successfully applied to the rapid determination of diflubenzuron in spiked mushroom samples of different mushroom species. The HPLC method was used like a comparative method to verify results. 相似文献
696.
The cationic polymerization of soybean oils was initiated by boron trifluoride diethyl etherate in supercritical carbon dioxide
medium. The resulting polymers had molecular weight ranging from 21,842 to 118,300 g/mol. Nuclear magnetic resonance spectroscopy
and gel permeation chromatography analysis confirmed the polymerization had occurred. Parameters affecting the polymerization
were studied, which included initiator amount and reaction time. Results show that the longer reaction time, up to 3 h, favored
the higher molecular weight of polymers at conditions of 140 °C and initiator BF3·OEt2 (2.5 g, 0.018 mol). When reaction time was increased further, the molecular weight of polymers stayed the same or slightly
decreased. Increased concentration of initiator gave the higher molecular weight of polymers. The high molecular weight polymers
were possibly formed through two path ways: polymerization and intermolecular Diels-Alder reaction. 相似文献
697.
GIS-based Probability Assessment of Natural Hazards in Forested Landscapes of Central and South-Eastern Europe 总被引:1,自引:0,他引:1
C. Lorz C. Fürst Z. Galic D. Matijasic V. Podrazky N. Potocic P. Simoncic M. Strauch H. Vacik F. Makeschin 《Environmental management》2010,46(6):920-930
We assessed the probability of three major natural hazards—windthrow, drought, and forest fire—for Central and South-Eastern
European forests which are major threats for the provision of forest goods and ecosystem services. In addition, we analyzed
spatial distribution and implications for a future oriented management of forested landscapes. For estimating the probability
of windthrow, we used rooting depth and average wind speed. Probabilities of drought and fire were calculated from climatic
and total water balance during growing season. As an approximation to climate change scenarios, we used a simplified approach
with a general increase of pET by 20%. Monitoring data from the pan-European forests crown condition program and observed
burnt areas and hot spots from the European Forest Fire Information System were used to test the plausibility of probability
maps. Regions with high probabilities of natural hazard are identified and management strategies to minimize probability of
natural hazards are discussed. We suggest future research should focus on (i) estimating probabilities using process based
models (including sensitivity analysis), (ii) defining probability in terms of economic loss, (iii) including biotic hazards,
(iv) using more detailed data sets on natural hazards, forest inventories and climate change scenarios, and (v) developing
a framework of adaptive risk management. 相似文献
698.
Kebede Amenu André Markemann Anne Valle Zárate 《Environmental monitoring and assessment》2013,185(11):9571-9586
The study aimed to assess the quality and health aspects of water intended for human and livestock consumption in two rural districts of the Rift Valley of Ethiopia. The study involved two parts: the first consisted of a questionnaire survey and farmers’ group discussions, complemented by secondary health data, and the second part determined the chemical (total dissolved solids, pH, manganese, hexa-valent chromium, fluoride) and microbiological quality of different water sources during dry and wet seasons. The result showed a lack of sustainable access to safe water in the communities. Industrial pollution and mismanagement of water sources by human and livestock was found to be a source of potential health risk. Potentially linked human health problems like malaria, diarrhoea and gastrointestinal parasites were common in the districts. Overall, 76 % of the assessed water sources (n?=?25) failed to comply with World Health Organization guidelines for human drinking water, for at least one assessed parameter, mostly irrespective of the season. The non-compliance was mainly attributed to Escherichia coli contamination and/or high fluoride concentration. At least 20 % of the water samples were also found to be unfit for livestock consumption based on assessed chemical parameters in both dry and wet seasons. To minimize the health risk associated with mismanagement and poor quality of water sources in the area, targeted action in the protection of surface water sources should be given priority. 相似文献
699.
We previously demonstrated that Cyanobacteria-derived microcystin-LR (MCLR) is able to induce cognitive dysfunction, but the mechanism is not understood. Long-term potential (LTP) in hippocampus is regarded as an important cellular mechanism of learning and memory. Here, the aim of this study was to evaluate the role of MCLR in LTP of hippocampal dentate gyrus (DG) by in vivo electrophysiological recording. We found that MCLR could suppress the induction of LTP in rat hippocampus, whereas simultaneous inhibition of glycogen synthase kinase-3β (GSK-3β) by LiCl or SB216763 attenuated the LTP impairments by MCLR. Furthermore, a decrease of the phosphorylated level at Ser9 of GSK-3β was observed by western blotting after intracerebroventricular (ICV) injection of MCLR, indicating GSK-3β was activated by MCLR. In addition, we showed that ICV administration of MCLR slightly stimulated activity of protein phosphatases (PPs) in the brain, which might activate GSK-3β via dephosphorylation of Ser9 site. Taken together, these findings demonstrated that GSK-3β plays a crucial role in regulating MCLR-induced cognitive deficit. 相似文献
700.
A.S. Al-Akel H.F. Alkahem Al-Balawi F. Al-Misned Z. Ahmad E.M. Suliman 《毒物与环境化学》2013,95(10):1865-1878
The influence of dietary copper (Cu) exposure on accumulation, growth, and hematological parameters was investigated in Cyprinus carpio after sub-chronic ingestion of 0, 250, 500, 750 or 1000?mg?kg?1 for 60 days. The profile of Cu accumulation among tissues in C. carpio was dependent on the exposure period and Cu concentration. Liver of C. carpio was the predominant storage tissue and the order of Cu accumulation in tissues was liver?>?intestine?> gill?>?kidney?>?muscle. Cu concentration at >125?mg?kg?1 reduced growth rate, and was inversely related to growth. The RNA?:?DNA ratios were not affected by exposure and there was no correlation between growth rate and RNA?:?DNA ratio in liver and muscle. There were no significant effects of exposure on blood parameters except for magnesium. Cu exposure time and dose increased the serum glutamic-oxaloacetic transaminase (SGOT) and serum glutamic-pyruvic transaminase (SGPT) activity levels. 相似文献